Editing Younger Dryas impact hypothesis (section)

== Evidence ==
[[File:Abu Hureyra meltglass.png|upright=1.5|thumb|alt=Meltglass from Abu Hureyra|Examples of [[Vitrified sand|meltglass]] from [[Tell Abu Hureyra]]{{hair space}}<ref name="Abu Hureyra">{{Cite Q|Q90119243|last1=Moore|first1=Andrew M. T.|author-link1=Andrew M. T. Moore|last2=Kennett|first2=James P.|author-link2=James P. Kennett|last3=Napier|first3=William M.|author-link3=William Napier (astronomer)|last4=Bunch|first4=Ted E.|last5=Weaver|first5=James C.|last6=LeCompte|first6=Malcolm|last7=Adedeji|first7=A. Victor|last8=Hackley|first8=Paul|last9=Kletetschka|first9=Gunther|last10=Hermes|first10=Robert E.|last11=Wittke|first11=James H.|last12=Razink|first12=Joshua J.|last13=Gaultois|first13=Michael W.|last14=West|first14=Allen|display-authors=8|name-list-style=vanc|quote=The wide range of evidence supports the hypothesis that a cosmic event occurred at Abu Hureyra ~12,800 years ago, coeval with impacts that deposited high-temperature meltglass, melted microspherules, and/or platinum at other YDB sites on four continents.}}</ref>]]
Proponents have offered as evidence for the impact event microscopic structures ([[Spherule|spherules]]), "black mats" of sediment they contend are evidence of widespread fires, their proposed dates for the [[Hiawatha crater]] in Greenland in the range of 12,800 years ago{{sfnp|Pino|Abarzúa|Astorga|Martel-Cea|2019}} (though later dates indicated an event from 55 million years ago), and the synchronous extinction of megafauna and associated impacts on prehistoric human societies. Proponents of the hypothesis say that these data cannot be adequately explained by volcanic, anthropogenic, or other natural processes.<ref name=Bunch/> They argue that the Younger Dryas boundary layer should be used as a local,<ref>{{Cite Q |Q106891675 |last=Andronikov |first=Alexandre V. |last2=Andronikova |first2=Irina E. |last3=Loehn |first3=Clayton W. |last4=Lafuente |first4=Barbara |last5=Ballenger |first5=Jesse A. M. |last6=Crawford |first6=George T. |last7=Lauretta |first7=Dante S. |author-link7=Dante Lauretta |name-list-style=vanc |quote=The presence of the high number of such microspherules in the sediments can serve as a local stratigraphic marker in identification of the [lower Younger Dryas boundary] there where dark variety of the black mat is absent.}}</ref> or even global <ref>{{Cite journal |author-link6=Albert Goodyear |author-link10=James P. Kennett |display-authors=8 |vauthors=Moore CR, West A, LeCompte MA, Brooks MJ, Daniel IR, Goodyear AC, Ferguson TA, Ivester AH, Feathers JK, Kennett JP, Tankersley KB, Adedeji AV, Bunch TE |date=March 2017 |title=Widespread platinum anomaly documented at the Younger Dryas onset in North American sedimentary sequences |journal=[[Scientific Reports]] |volume=7 |issue=1 |page=44031 |bibcode=2017NatSR...744031M |doi=10.1038/srep44031 |pmc=5343653 |pmid=28276513 |quote=We expect the Pt anomaly to serve as a widely-distributed time marker horizon (datum) for identification and correlation of the onset of the YD climatic episode at 12,800 Cal B.P. This Pt datum will facilitate the dating and correlating of archaeological, paleontological, and paleoenvironmental data between sequences, especially those with limited age control.}}</ref> [[Marker horizon|stratigraphic marker]].

=== Impact debris ===
Proponents, most of whom are scientists, have reported materials including [[nanodiamonds]], metallic microspherules, carbon spherules, magnetic [[microspherulite|spherules]], [[iridium]], [[platinum]], platinum/[[palladium]] ratios, charcoal, soot, and [[fullerene]]s enriched with [[helium-3]] that they interpret as evidence for an impact event that marks the beginning of the Younger Dryas.<ref name="Dalton" /><ref name="Wittke b">{{Cite journal |author-link4=James P. Kennett |author-link6=Andrew M. T. Moore |author-link7=Gordon Hillman |author-link9=Albert Goodyear |display-authors=8 |vauthors=Wittke JH, Weaver JC, Bunch TE, Kennett JP, Kennett DJ, Moore AM, Hillman GC, Tankersley KB, Goodyear AC, Moore CR, Daniel IR, Ray JH, Lopinot NH, Ferraro D, Israde-Alcántara I, Bischoff JL, DeCarli PS, Hermes RE, Kloosterman JB, Revay Z, Howard GA, Kimbel DR, Kletetschka G, Nabelek L, Lipo CP, Sakai S, West A, Firestone RB |date=June 2013 |title=Evidence for deposition of 10 million tonnes of impact spherules across four continents 12,800 y ago |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=110 |issue=23 |pages=E2088–97 |bibcode=2013PNAS..110E2088W |doi=10.1073/pnas.1301760110 |pmc=3677428 |pmid=23690611 |doi-access=free}}</ref> One of the most widely publicized discoveries (nanodiamonds in Greenland) has never been verified and is disputed.<ref name="Kurbatov Mayewski Steffensen West 2022">{{cite web |last1=Kurbatov |first1=Andrei V. |last2=Mayewski |first2=Paul A. |last3=Steffensen |first3=Jorgen P. |last4=West |first4=Allen |last5=Kennett |first5=Douglas J. |last6=Kennett |first6=James P. |last7=Bunch |first7=Ted E. |last8=Handley |first8=Mike |last9=Introne |first9=Douglas S. |date=2022-09-20 |title=Discovery of a nanodiamond-rich layer in the Greenland ice sheet |url=https://pubpeer.com/publications/28B83ADB820618B3F374667D5FBB92 |access-date=2022-09-28 |website=PubPeer |last10=Hee |first10=Shane S. Que |last11=Mercer |first11=Christopher |last12=Sellers |first12=Marilee |last13=Shen |first13=Feng |last14=Sneed |first14=Sharon B. |last15=Weaver |first15=James C. |last16=Wittke |first16=James H. |last17=Stafford |first17=Thomas W. |last18=Donovan |first18=John J. |last19=Xie |first19=Sujing |last20=Razink |first20=Joshua J. |last21=Stich |first21=Adrienne |last22=Kinzie |first22=Charles R. |last23=Wolbach |first23=Wendy S.}}</ref>

Some scientists have asserted that the carbon spherules originated as fungal structures and/or insect fecal pellets, and contained modern contaminants<ref name="Boslough" /><ref name="spherules">{{Cite web |last=Roach |first=John |name-list-style=vanc |date=22 June 2010 |title=Fungi, Feces Show Comet Didn't Kill Ice Age Mammals? |url=https://www.nationalgeographic.com/science/article/100622-science-environment-wildfires-cooling-ice-age-extinctions |url-access=limited |url-status=live |archive-url=https://web.archive.org/web/20210717200455/https://www.nationalgeographic.com/science/article/100622-science-environment-wildfires-cooling-ice-age-extinctions |archive-date=17 July 2021 |access-date=17 July 2021 |website=[[National Geographic]]}}</ref> and that the claimed nanodiamonds are actually misidentified [[graphene]] and graphene/[[graphane]] oxide aggregates.<ref name="Daulton">{{Cite journal |author-link3=Andrew Cunningham Scott |vauthors=Daulton TL, Pinter N, Scott AC |date=September 2010 |title=No evidence of nanodiamonds in Younger-Dryas sediments to support an impact event |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=107 |issue=37 |pages=16043–7 |bibcode=2010PNAS..10716043D |doi=10.1073/pnas.1003904107 |pmc=2941276 |pmid=20805511 |doi-access=free}}</ref><ref name="Kerr2">{{Cite web |last=Kerr |first=Richard A. |author-link=Richard Kerr (science journalist) |name-list-style=vanc |date=30 October 2010 |title=Mammoth-Killer Impact Rejected |url=https://www.science.org/content/article/mammoth-killer-impact-rejected |url-status=live |archive-url=https://web.archive.org/web/20180917181633/http://www.sciencemag.org/news/2010/08/mammoth-killer-impact-rejected |archive-date=17 September 2018 |access-date=17 September 2018 |website=Science NOW |publisher=[[American Association for the Advancement of Science|AAAS]]}}</ref> Iridium, magnetic minerals, microspherules, carbon, and nanodiamonds are all subject to differing interpretations as to their nature and origin, and may be explained in many cases by purely terrestrial or non-catastrophic factors.<ref name="PinterandIshman2008">{{Cite journal |vauthors=Pinter N, Ishman SE |year=2008 |title=Impacts, mega-tsunami, and other extraordinary claims |journal=[[GSA Today]] |volume=18 |issue=1 |pages=37–38 |doi=10.1130/GSAT01801GW.1 |doi-access=free}}</ref><ref name="No love">{{Cite web |date=23 April 2012 |title=No Love for Comet Wipeout |url=https://www.science.org/content/article/no-love-comet-wipeout |url-status=live |archive-url=https://web.archive.org/web/20180917181709/http://www.sciencemag.org/news/2012/04/no-love-comet-wipeout |archive-date=17 September 2018 |access-date=17 September 2018 |publisher=[[Science (journal)|Science]] |vauthors=Perkins S}}</ref> An analysis of a similar Younger Dryas boundary layer in Belgium yielded carbon crystalline structures such as nanodiamonds, but the authors concluded that they also did not show unique evidence for a bolide impact.<ref>{{Cite journal |vauthors=Tian H, Schryvers D, Claeys P |date=January 2011 |title=Nanodiamonds do not provide unique evidence for a Younger Dryas impact |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=108 |issue=1 |pages=40–4 |bibcode=2011PNAS..108...40T |doi=10.1073/pnas.1007695108 |pmc=3017148 |pmid=21173270 |doi-access=free}}</ref> One group of researchers also reported they were unable to replicate [[platinum group]] metals in the boundary layer,{{efn|One of the authors of this study, Matthew Boyd,<ref name="Absence of geochemical evidence" /> later published a paper that argued in favour of the impact hypothesis.<ref>{{Cite Q |Q106863462 |last1=Teller |first1=James |last2=Boyd |first2=Matthew |last3=LeCompte |first3=Malcolm |last4=Kennett |first4=James P. |author-link4=James P. Kennett |last5=West |first5=Allen |last6=Telka |first6=Alice |last7=Diaz |first7=Aura |last8=Adedeji |first8=Victor |last9=Batchelor |first9=Dale |last10=Mooney |first10=Charles |last11=Garcia |first11=Roberto |display-authors=8 |name-list-style=vanc |quote=We propose that this massive hydrological reorganization resulted from a cosmic impact event at the YD boundary.}}</ref>}}<ref name="Absence of geochemical evidence">{{Cite journal |author-link7=Vance T. Holliday |author-link8=Vance Haynes |display-authors=8 |vauthors=Paquay FS, Goderis S, Ravizza G, Vanhaeck F, Boyd M, Surovell TA, Holliday VT, Haynes CV, Claeys P |date=December 2009 |title=Absence of geochemical evidence for an impact event at the Bølling-Allerød/Younger Dryas transition |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=106 |issue=51 |pages=21505–10 |bibcode=2009PNAS..10621505P |doi=10.1073/pnas.0908874106 |pmc=2799824 |pmid=20007789 |doi-access=free}}</ref> despite reporting enhanced Iridium concentrations up to >300% of background in 2 of their samples. <ref name="Geochemical data do not refute">{{Cite journal |display-authors=8 |vauthors=Bunch, TE, West, A, Firestone, RB, Kennett, JP, Wittke, JH, Kinzie, CR, Wolbach, WS |date=April 2010 |title=Geochemical data reported by Paquay et al. do not refute Younger Dryas impact event |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=107 |issue=15 |pages=E58; author repliy E59-60 |doi=10.1073/pnas.1001156107 |pmid=20388907 |pmc=2872453 |bibcode=2010PNAS..107E..58B |doi-access=free}}</ref> Another group was unable to confirm prior claims of magnetic particles and microspherules in 2009,<ref>{{Cite journal |author-link2=Vance T. Holliday |author-link5=Vance Haynes |display-authors=8 |vauthors=Surovell TA, Holliday VT, Gingerich JA, Ketron C, Haynes CV, Hilman I, Wagner DP, Johnson E, Claeys P |date=October 2009 |title=An independent evaluation of the Younger Dryas extraterrestrial impact hypothesis |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=106 |issue=43 |pages=18155–8 |bibcode=2009PNAS..10618155S |doi=10.1073/pnas.0907857106 |pmc=2775309 |pmid=19822748 |doi-access=free}}</ref> though all subsequent studies successfully replicated them, including multiple independent teams.<ref>{{Cite journal |display-authors=1 |vauthors=Haynes, CV |date=October 2010 |title=The Murray Springs Clovis site, Pleistocene extinction, and the question of extraterrestrial impact |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=107 |issue=9 |pages=4010–5 |doi=10.1073/pnas.0908191107 |pmid=20160115 |pmc=2840150 |bibcode=2010PNAS..107.4010H |doi-access=free}}</ref><ref>{{Cite journal |display-authors=7 |vauthors=LeCompte MA, Goodyear AC, Demitroff MN, Batchelor D, Vogel EK, Mooney C, Rock BN, Siedel AW |date=October 2012 |title=Independent evaluation of conflicting microspherule results from different investigations of the Younger Dryas impact hypothesis |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=109 |issue=44 |pages=E2960-9 |doi=10.1073/pnas.1208603109 |pmid=22988071 |pmc=3497834 |doi-access=free}}</ref><ref name="10.1111_geoa.12122"/><ref>{{Cite journal |display-authors=8 |vauthors=Kletetschka G, Vondrak D, Hruba J, Prochazka V, Nabelek L, Svitavska-Svoboda H, Bobek P, Horicka Z, Kadlec J, Takac M, Stuchlik E |date=October 2018 |title=Cosmic-impact event in lake sediments from central Europe postdates the Laacher See Eruption and marks onset of the Younger Dryas |journal=The Journal of Geology |volume=126 |issue=6 |pages=561–575 |doi=10.1086/699869 |bibcode=2018JG....126..561K |doi-access=free}}</ref><ref>{{Cite journal |display-authors=8 |vauthors=Teller J, Boyd M, LeCompte MA, Kennett JP, West A, Telka A, Diaz A, Adedeji V, Batchelor D, Mooney C, Garcia R |date=October 2019 |title=A multi-proxy study of changing environmental conditions in a Younger Dryas sequence in southwestern Manitoba, Canada, and evidence for an extraterrestrial event |journal=Quaternary Research |volume=93 |pages=60–87  |doi=10.1017/qua.2019.46|s2cid=210614208 }}</ref>
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  * A list of news articles about the YDIH featuring Mark Boslough can be generated from Wikidata with this query:
      https://w.wiki/4cK$

  * A list of news articles about the YDIH that also talk about airbursts can be generated from Wikidata with this query:
      https://w.wiki/4cQ9

  * The Scholia profile (which also utilises Wikidata) is really useful here as well:
      https://scholia.toolforge.org/topic/Q1092095
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=== "Black mats" ===
The evidence given by proponents of a [[bolide]] or [[meteorite]] impact event includes "black mats", or [[stratum|strata]] of organic-rich [[soil]] that have been identified at about 50 [[archaeological site]]s across North America.{{efn|name=Black mat note|The darkened [[stratum]] was first identified at the [[Lehner Mammoth-Kill Site]] by [[Emil Haury]] who named it "Lehner swamp soil";<ref>{{Cite Q |Q59224169 |author-link1=Emil Haury |last=Haury |first=Emil W. |last2=Sayles |first2=E. B. |last3=Wasley |first3=William W. |name-list-style=vanc}}</ref> it was later renamed by [[Vance Haynes#"Black mat" layers|Vance Haynes]] as the "black mat".<ref>{{Cite web |title= Paleoindian Studies and Geoarchaeology at the University of Arizona |url=http://www.argonaut.arizona.edu/history.htm |url-status=dead |archive-url=https://web.archive.org/web/20180723064120/http://www.argonaut.arizona.edu/history.htm |archive-date=2018-07-23 |website=[[University of Arizona]] |quote=Vance Haynes later renamed it the 'black mat'}}</ref><ref name="PNAS07A" />}} Using statistical analysis and modeling, [[James P. Kennett]] and others concluded that widely separated organic-rich layers, including ''black mats'', were deposited synchronously across multiple continents as an identifiable ''Younger Dryas boundary layer''.<ref>{{Cite Q|Q35718070|last1=Kennett|first1=James P|last2=Kennett|first2=Douglas J|last3=Culleton|first3=Brendan J|last4=Tortosa|first4=J Emili Aura|last5=Bischoff|first5=James L|last6=Bunch|first6=Ted E|last7=Daniel|first7=I Randolph|last8=Erlandson|first8=Jon M|last9=Ferraro|first9=David|last10=Firestone|first10=Richard B|last11=Goodyear|first11=Albert C|last12=Israde-Alcántara|first12=Isabel|last13=Johnson|first13=John R|last14=Pardo|first14=Jesús F Jordá|last15=Kimbel|first15=David R|last16=LeCompte|first16=Malcolm A|last17=Lopinot|first17=Neal H|last18=Mahaney|first18=William C|last19=Moore|first19=Andrew M T|last20=Moore|first20=Christopher R|last21=Ray|first21=Jack H|last22=Stafford|first22=Thomas W|last23=Tankersley|first23=Kenneth Barnett|last24=Wittke|first24=James H|last25=Wolbach|first25=Wendy S|last26=West|first26=Allen|author-link1=James P. Kennett|author-link8=Jon M. Erlandson|author-link11=Albert Goodyear|author-link19=Andrew M. T. Moore|display-authors=8|name-list-style=vanc}}</ref> In 2019, Jorgeson and others tested this conclusion with the simulation of radiocarbon ages.<ref name="JorgesonOthers2020a">{{Cite journal |last1=Jorgeson |first1=Ian A. |last2=Breslawski |first2=Ryan P. |last3=Fisher |first3=Abigail E. |name-list-style=vanc |date=13 February 2020 |title=Radiocarbon simulation fails to support the temporal synchroneity requirement of the Younger Dryas impact hypothesis |url=https://www.cambridge.org/core/journals/quaternary-research/article/abs/radiocarbon-simulation-fails-to-support-the-temporal-synchroneity-requirement-of-the-younger-dryas-impact-hypothesis/6478BF9FD2E63B22C6152075E1B5C089 |url-status=live |journal=[[Quaternary Research]] |volume=96 |pages=123–139 |bibcode=2020QuRes..96..123J |doi=10.1017/qua.2019.83 |issn=1096-0287 |archive-url=https://web.archive.org/web/20210620182032/https://www.cambridge.org/core/journals/quaternary-research/article/abs/radiocarbon-simulation-fails-to-support-the-temporal-synchroneity-requirement-of-the-younger-dryas-impact-hypothesis/6478BF9FD2E63B22C6152075E1B5C089 |archive-date=20 June 2021 |s2cid=213657406}}</ref> They accounted for measurement error, calibration uncertainty, "[[old wood]]" effects, and laboratory measurement biases, and compared against the dataset of radiocarbon ages for the [[Laacher See]] eruption. They found the Laacher See 14C dataset to be consistent with expectations of synchroneity. They found the Younger Dryas boundary layer 14C dataset to be inconsistent with the expectations for its synchroneity, and the synchronous global deposition of the hypothesized Younger Dryas boundary layer to be extremely unlikely.<ref name="JorgesonOthers2020a" />